1 files changed, 16 insertions, 10 deletions
diff --git a/activerecord/lib/active_record/connection_adapters/mysql_adapter.rb b/activerecord/lib/active_record/connection_adapters/mysql_adapter.rb
index 521bd810d0..8a19c7af00 100644
--- a/activerecord/lib/active_record/connection_adapters/mysql_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/mysql_adapter.rb
@@ -183,7 +183,7 @@ module ActiveRecord
       QUOTED_TRUE, QUOTED_FALSE = '1'.freeze, '0'.freeze
 
       NATIVE_DATABASE_TYPES = {
-        :primary_key => "int(11) DEFAULT NULL auto_increment PRIMARY KEY".freeze,
+        :primary_key => { :name => "DEFAULT NULL auto_increment PRIMARY KEY", :limit => 4 },
         :string      => { :name => "varchar", :limit => 255 },
         :text        => { :name => "text" },
         :integer     => { :name => "int", :limit => 4 },
@@ -541,15 +541,21 @@ module ActiveRecord
 
       # Maps logical Rails types to MySQL-specific data types.
       def type_to_sql(type, limit = nil, precision = nil, scale = nil)
-        return super unless type.to_s == 'integer'
-
-        case limit
-        when 1; 'tinyint'
-        when 2; 'smallint'
-        when 3; 'mediumint'
-        when nil, 4, 11; 'int(11)'  # compatibility with MySQL default
-        when 5..8; 'bigint'
-        else raise(ActiveRecordError, "No integer type has byte size #{limit}")
+        case type.to_s
+        when 'primary_key'
+          native = native_database_types[:primary_key]
+          return type_to_sql('integer', limit) + ' ' + native[:name]
+        when 'integer'
+          case limit
+          when 1; 'tinyint'
+          when 2; 'smallint'
+          when 3; 'mediumint'
+          when nil, 4, 11; 'int(11)'  # compatibility with MySQL default
+          when 5..8; 'bigint'
+          else raise(ActiveRecordError, "No integer type has byte size #{limit}")
+          end
+        else
+          super
         end
       end